Magnesium base alloy



Patented Oct. 22, 1940 UNITED STATES PATENT OFFICE Bitterield, Germany,

assignors, by mesne assignments, to Magnesium Development Corporation, a corporation of Delaware No Drawing.

Application November 18, 1939, Se-

rial No. 305,172 In Germany November 30,

8 Claim 5.

This invention relates to magnesium base alloys.

In the course of systematic research work conducted with a view to finding alloying constitu- 5 ents which, even in extremely small quantities,

cause a refining of the inherently coarse crystalline structure of pure magnesium on solidification from the molten state, and thus produce a corresponding improvement of the mechanical strength properties of the metal, we have found that, on causing an alloy of magnesium with a minor percentage of yttrium to solidify from the molten state, the grain size of the metal is considerably reduced as compared with a metal in which yttrium is absent. An addition of yttrium in the order of magnitude of 0.1% to pure magnesium alloys already produces a very substantial grain refinement which may be still further enhanced by adding larger amounts of yttrium.,

20 The present invention accordingly contemplates magnesium base alloys containing yttrium, in which the yttrium content may vary between about 0.1 and about 10%; preferably, however, the yttrium content is not increased beyond about 4% of the weight of the alloy.

Owing to the substantial grain refinement produced by the incorporation oi yttrium, the mechanical strength properties oi binary alloys oi magnesium containing about 0.1% and more oi 30 yttrium, are materially superior to those oi pure magnesium; this is evident from the following table which illustrates the results of tensile tests oi samples which were cast into sand moulds.

35 Tensile Elonga- Contrac- Yield strength tion, tion, point kgJmin. percent percent kgJmm.

1 Pure magnesium. 9-13 6-6 3.0 2 Puremagneslum 40 containing 3 mrcsnt of Y a P umma m" 15.9 16.0 6.0

uremagn um containing 2 figment oi yt- Owing to the low content oi alloying constitucuts, the binary magnesium-yttrium alloys in which the yttrium content is kept below about 4% 50v have every narrow interval oi solidification; this causes mould castings produced irom these alloys to be essentially iree irom microshrinkage and also aiiords good welding properties oi the alloys. In contradistinction to other similar cases it has been observed that manganese may be added to the magnesium-yttrium alloys without detrimentally affecting the grain-refining effect of yttrium. The quantity of manganese added may be of the same order (e. g. 2% of the weight of the alloy) as that which is customary in the case of pure magnesium. The addition of manganese produces a substantial improvement in resistance to corrosion of the alloys, while the tensile strength values of the binary magnesium-yttrium alloys are in no way impaired.-

We claim:

1. A magnesium base alloy containing yttrium in a quantity ranging between about 0.1 and about by weight of the alloy and also between about 0.1 and about 2% of manganese.

2. An alloy consisting of between about 0.1 and about 10% of yttrium, the balance being substantially pure magnesium.

3. An alloy consisting of between about 0.1 and about 4% of yttrium, the balance being substantially pure magnesium.

4. An alloy consisting of between about 0.1

and about 10% of yttrium, and also about 2% of manganese, the balance being substantially pure magnesium.

5. A binary alloy consisting of about 0.3% of yttrium, the balance being substantially pure magnesium.

' 6. A binary alloy consisting of about 2.5% oi yttrium, the balance being substantially pure magnesium.

'1. A magnesium base alloy containing yttrium and characterized by a finer grain structure and greater mechanical strength than a magnesium base alloy oi similar composition but without yttrium, the yttrium content oi said alloy rang- 'ing between about 0.1 per cent and about 10 per cent by weight oi the alloy, the remainder of the alloy comprising magnesium and any other metal or metals not subversive oi the above characteristics.

8. A magnesium base alloy containing yttrium and characterized by a finer grain structure, greater mechanical strength, and betterv casting properties than a magnesium base alloy oi similar composition but without yttrium, the yttrium content oi said alloy ranging between about 0.1 per cent and about 4 per cent by weight oi the alloy, the remainder oi the alloy comprising magnesium and any other metal or metals not subversive oi the above characteristics.

FRAN Z SAUERWALD. HANS EIBENREICH. 

